What if you could find a sunscreen that went on completely clear and worked better the more you were out in the sun? What if that sunscreen was made out of DNA?

Researchers at Binghamton University, State University of New York have developed a coating made out of DNA that does just that. The scientists found that the more of their DNA-based sunscreen is exposed to light, the better it is at protecting skin from ultraviolet light. Plus it keeps your skin hydrated.

"Ultraviolet (UV) light can actually damage DNA, and that's not good for the skin," said Guy German, assistant professor of biomedical engineering at Binghamton University. "We thought, let's flip it. What happens instead if we actually used DNA as a sacrificial layer? So instead of damaging DNA within the skin, we damage a layer on top of the skin."

German and a team of researchers developed thin and optically transparent crystalline DNA films and irradiated them with UV light. They found that the more they exposed the film to UV light, the better the film got at absorbing it.

"If you translate that, it means to me that if you use this as a topical cream or sunscreen, the longer that you stay out on the beach, the better it gets at being a sunscreen," said German.

As an added bonus, the DNA coatings are also hygroscopic, meaning that skin coated with the DNA films can store and hold water much more than uncoated skin. When applied to human skin, they are capable of slowing water evaporation and keeping the tissue hydrated for extended periods of time.

German intends to see next if these materials might be good as a wound covering for hostile environments where 1) you want to be able to see the wound healing without removing the dressing, 2) you want to protect the wound from the sun and 3) you want to keep the wound in a moist environment, known to promote faster wound healing rates.

"Not only do we think this might have applications for sunscreen and moisturizers directly, but if it's optically transparent and prevents tissue damage from the sun and it's good at keeping the skin hydrated, we think this might be potentially exploitable as a wound covering for extreme environments," he said.

In the US, sunscreens are regulated as a drug, so further testing and going through the drug approval process would be required before the product would come to market.

Quaternary ammonium compounds are a class of chemicals commonly used in shampoos, conditioners, disinfectants, and almost every kind of cosmetic item on the market. "Quats" for short, have anti-static, disinfectant, preservative, and conditioning properties. A recent study has found that two common quats, alkyl dimethyl benzyl ammonium chloride (aka benzalkonium chloride) and didecyl dimethyl ammonium chloride (aka quaternium-12) used in combination caused birth defects in animal studies.

In April, the FTC came to settlement agreements with four companies making allegedly false "All-Natural" claims. On July 13th, Following a public comment period, the Federal Trade Commission has approved four final consent orders against companies that allegedly misrepresented their personal care products as “All-Natural” or “100% Natural,” despite the fact that they contain man-made ingredients.

Under the final settlements, each of the companies is barred from making similar misrepresentations in the future and must have competent and reliable evidence to substantiate any ingredient-related, environmental, or health claims it makes.

The Commission vote approving the final orders and responses to the public commenters was 3-0. (The staff contact is Robert Frisby, Bureau of Consumer Protection, 202-326-2098.)

A nanoparticle commonly used in food, cosmetics, sunscreen and other products can have subtle effects on the activity of genes expressing enzymes that address oxidative stress inside two types of cells. While the titanium dioxide (TiO2) nanoparticles are considered "non-toxic" because they don't kill cells at low concentrations, these cellular effects could add to concerns about long-term exposure to the nanomaterial.

Researchers at the Georgia Institute of Technology used high-throughput screening techniques to study the effects of titanium dioxide nanoparticles on the expression of 84 genes related to cellular oxidative stress. Their work found that six genes, four of them from a single gene family, were affected by a 24-hour exposure to the nanoparticles.

The effect was seen in two different kinds of cells exposed to the nanoparticles: human HeLa cancer cells commonly used in research, and a line of monkey kidney cells. Polystyrene nanoparticles similar in size and surface electrical charge to the titanium dioxide nanoparticles did not produce a similar effect on gene expression.

"This is important because every standard measure of cell health shows that cells are not affected by these titanium dioxide nanoparticles," said Christine Payne, an associate professor in Georgia Tech's School of Chemistry and Biochemistry. "Our results show that there is a more subtle change in oxidative stress that could be damaging to cells or lead to long-term changes. This suggests that other nanoparticles should be screened for similar low-level effects."

The research was reported online May 6 in the Journal of Physical Chemistry C. The work was supported by the National Institutes of Health (NIH) through the HERCULES Center at Emory University, and by a Vasser Woolley Fellowship.

Titanium dioxide nanoparticles help make powdered donuts white, protect skin from the sun's rays and reflect light in painted surfaces. In concentrations commonly used, they are considered non-toxic, though several other studies have raised concern about potential effects on gene expression that may not directly impact the short-term health of cells.

To determine whether the nanoparticles could affect genes involved in managing oxidative stress in cells, Payne and colleague Melissa Kemp - an associate professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University - designed a study to broadly evaluate the nanoparticle's impact on the two cell lines.

Working with graduate students Sabiha Runa and Dipesh Khanal, they separately incubated HeLa cells and monkey kidney cells with titanium oxide at levels 100 times less than the minimum concentration known to initiate effects on cell health. After incubating the cells for 24 hours with the TiO2, the cells were lysed and their contents analyzed using both PCR and Western Blot techniques to study the expression of 84 genes associated with the cells' ability to address oxidative processes.

Payne and Kemp were surprised to find changes in the expression of six genes, including four from the peroxiredoxin family of enzymes that helps cells degrade hydrogen peroxide, a byproduct of cellular oxidation processes. Too much hydrogen peroxide can create oxidative stress which can damage DNA and other molecules.

The effect measured was significant - changes of about 50 percent in enzyme expression compared to cells that had not been incubated with nanoparticles. The tests were conducted in triplicate and produced similar results each time.

"One thing that was really surprising was that this whole family of proteins was affected, though some were up-regulated and some were down-regulated," Kemp said. "These were all related proteins, so the question is why they would respond differently to the presence of the nanoparticles."

The researchers aren't sure how the nanoparticles bind with the cells, but they suspect it may involve the protein corona that surrounds the particles. The corona is made up of serum proteins that normally serve as food for the cells, but adsorb to the nanoparticles in the culture medium. The corona proteins have a protective effect on the cells, but may also serve as a way for the nanoparticles to bind to cell receptors.

Titanium dioxide is well known for its photo-catalytic effects under ultraviolet light, but the researchers don't think that's in play here because their culturing was done in ambient light - or in the dark. The individual nanoparticles had diameters of about 21 nanometers, but in cell culture formed much larger aggregates.

In future work, Payne and Kemp hope to learn more about the interaction, including where the enzyme-producing proteins are located in the cells. For that, they may use HyPer-Tau, a reporter protein they developed to track the location of hydrogen peroxide within cells.

The research suggests a re-evaluation may be necessary for other nanoparticles that could create subtle effects even though they've been deemed safe.

"Earlier work had suggested that nanoparticles can lead to oxidative stress, but nobody had really looked at this level and at so many different proteins at the same time," Payne said. "Our research looked at such low concentrations that it does raise questions about what else might be affected. We looked specifically at oxidative stress, but there may be other genes that are affected, too."

Those subtle differences may matter when they're added to other factors.

"Oxidative stress is implicated in all kinds of inflammatory and immune responses," Kemp noted. "While the titanium dioxide alone may just be modulating the expression levels of this family of proteins, if that is happening at the same time you have other types of oxidative stress for different reasons, then you may have a cumulative effect."

Scientists from Oregon State University say that triclosan, an antibacterial agent found in many products ranging from hand soaps to toys and even toothpaste, can rapidly disrupt bacteria found in the gut.

In the new study, researchers found that triclosan exposure caused rapid changes in both the diversity and composition of the microbiome in the laboratory animals. It's not clear what the implication may be for animal or human health, but scientists believe that compromising of the bacteria in the intestinal tract may contribute to the development or severity of disease.

"There has been a legacy of concern about exposure to microbial pathogens, which has led to increased use of these antimicrobial products," said Thomas Sharpton, an assistant professor of microbiology and statistics in the OSU Colleges of Science and Agricultural Sciences, and corresponding author on the new study.

"However, there's now a growing awareness of the importance of the bacteria in our gut microbiome for human health, and the overuse of antibiotics that can lead to the rise of 'superbugs.' There are consequences to constantly trying to kill the bacteria in the world around us, aspects we're just beginning to understand."

Some bacteria were more susceptible to the impact of triclosan than others, such as the family Enterobacteriaceae; and others were more resilient, such as the genus Pseudomonas.

Triclosan was first used as a hospital scrub in the 1970s and now is one of the most common antimicrobial agents in the world, found in shampoos, deodorants, toothpastes, mouth washes, kitchen utensils, cutting boards, toys, bedding, socks and trash bags. It continues to be used in medical settings, and can be easily absorbed through the skin.

"Clearly there may be situations where antibacterial agents are needed," said Christopher Gaulke, lead author on the study and a postdoctoral microbiology researcher in the OSU College of Science.

"However, scientists now have evidence that intestinal bacteria may have metabolic, cardiovascular, autoimmune and neurological impacts, and concerns about overuse of these agents are valid. Cumulative impacts are also possible. We need to do significantly more evaluation of their effects, some of which might be dramatic and long lasting."

The gut-associated microbiome performs vital functions for human health, prevents colonization with pathogens, stimulates the development of the immune system, and produces micronutrients needed by the host. Dysfunction of this microbiome has been associated with human disease, including diabetes, heart disease, arthritis and malnutrition, the scientists pointed out in their study.

Humans are routinely exposed to an array of chemicals, metals, preservatives, microbes and nutrients, some of which may be beneficial, some innocuous, and others harmful, the researchers said. Part of the strength of the present study is developing improved ways, through rapid screening of zebrafish, to more easily determine which compounds may be acceptable and which are toxic, scientists say.

Triclosan has been a concern in part because it is so widely used, and it's also readily absorbed through the skin and gastrointestinal tracts, showing up in urine, feces and breast milk. It also has been associated with endocrine disruption in fish and rats, may act as a liver tumor promoter, and can alter inflammatory responses.

This study showed it was quickly associated with shifts in the microbial community structure and can alter the abundance of specific taxa.

Collaborators on this research included scientists from the OSU Environmental Health Sciences Center and OSU College of Agricultural Sciences.